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Severe WX Severe Weather Threats 1/21-1/22 2017 (Saturday - Sunday)

Like I said earlier, not only does the warm front need to make it as far north as the watch goes, but it has a lot of work to do to get things destabilized once it gets there (if it does). Where I am about 12-15 miles north of Birmingham I have a temp of 57 (and falling) with a dew point of 54.
 
The low is closer as well as a warm front....that is what they're seeing, I believe...
 
Current surface based cape:

sbcp.gif
 
Yeah I've been watching the mesoanalysis expecting something dramatic to happen and it...hasn't yet.

Looks like there's still plenty of action going back in LA/AR though, right in that lovely radar hole.
 
This quote from the new Day 1 Outlook is key from the SPC's perspective of how this event will evolve overnight:

"The low-level jet should
undergo a significant increase over the Gulf Coast states tonight in
response to mass adjustments within exit region of approaching upper
jet. This process will promote additional thunderstorm development
along and just north of the warm front with theta-e advection
beneath steep mid-level lapse rate plume contributing to moderate instability."
 
Down to 54\54 here. That cooler airmass is established pretty good. If a good MCS gets going on the warm front, it will be very hard for it to get northward.
 
GTWXAlum said:
This quote from the new Day 1 Outlook is key from the SPC's perspective of how this event will evolve overnight:

"The low-level jet should
undergo a significant increase over the Gulf Coast states tonight in
response to mass adjustments within exit region of approaching upper
jet. This process will promote additional thunderstorm development
along and just north of the warm front with theta-e advection
beneath steep mid-level lapse rate plume contributing to moderate instability."
Click to expand...

They've still gotta be expecting the warm front to make some significant progress to the north, then, right?
 
http://www.spc.noaa.gov/products/md/md0098.html

Mesoscale Discussion 0098
NWS Storm Prediction Center Norman OK
0814 PM CST Sat Jan 21 2017
Areas affected...Parts of southeast Louisiana into adjacent southern
Mississippi
Concerning...Tornado Watch 15...
Valid 220214Z - 220315Z
The severe weather threat for Tornado Watch 15 continues.
SUMMARY...Severe/tornado risk continues to gradually shift northeast
out of Tornado Watch 15 into adjacent watches.
DISCUSSION...Latest radar loop shows isolated strong/locally severe
storms moving east-northeast across parts of southeast Louisiana
mainly north of I-10/I-12, near and north of the slowly
northward-advancing warm front. The evening LIX RAOB revealed a
very potent severe-storm environment -- both kinematically and
thermodynamically -- in the vicinity of the front, which continues
to spread northeast into parts of Mississippi and Alabama. Though
local risk may linger across WW 15 beyond the scheduled 22/03Z
expiration, expect the main severe/tornado potential to shift north
of the watch over the next couple of hours.
 
Haven't had much time to dig deep into things this evening but I think we need to remember that we are in Jan. Dewpoints are not required to be in the 60's when you add shear plus increasing bouyancy/lapse rates. This has been my concern all along...you do not need 1000 cape...with low level shear only 50/100 cape can do the job-seen it happen many times. Because of this, I thought they were not going far enough north. Still yet to be seen...but I think that is part of the decision making.
 
One thing that can give you an idea about how a system is going to go is what storms do with limited instability. For instance that wrapped up storm in Scott County Ms. According to the SPC meso analysis page that storm is at BEST tapping into 500j cape.
 
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